on the line of rails:-The pilot engine precedes the locomotive from one to two iniles, or such a distance as will enable the engineer to overcome the momentum of the train; should any obstacle cause the pilot engine to stop, the governor will of course stop also, and the balls descending will force down the stem d, until one of the springs c, comes on the part o of the stem, which is made of ivory or any other non-conducting substance, thereby instantly breaking the electric current, which had been transmitted, as before described, from the battery through the coil of wire and magnet. The result is, that the coil of wire not being any longer under the influence of the electric current, returns to the horizontal position, and points to the word "dangerous." A detent is at the same time released when a piece of clock work begins to run down, first striking a signal on a bell k, or gong, or sounding a whistle, and next, by means of the levers s t, releasing a weight u, which shuts off the steam. The clock work, or apparatus, by which the signal is sounded, steam shut off, &c., is so contrived as to be wound up by the motion of the locomotive engine, and is therefore always available; at the same time, by means of a very simple provision, over-winding is prevented.

In the event of any obstacle lying on the rails, the slipping of an embankment, or displacement of a rail, by which the progress of the pilot engine is impeded, or diverted from its proper course, the sig nalling and ultimate stopping of the train is effected with certainty. It is also proposed to connect the conducting wires with the gates at crossings, so that on a gate being left open, the pilot engine stops short before it reaches it, and thereby prevents accidents. The intersections of cross lines of railways are also arranged, so that on two trains coming up to the crossing at the same time, the one that is foremost stops the approach of the other until it has passed, and thereby prevents collision.

With respect to the transmission of the electric current of the voltaic battery, it has been proved by experiment, that for a distance of five or six miles this may be accomplished with certainty, and also that the conducting power of the wires is not affected by moisture; as it is contemplated that the distance between the

99

pilot and the locomotive engine need never exceed two miles, it seems probable that this subtle agent may be ap. plied in the manner proposed with every prospect of success.

The action of the models now exhibiting at the Royal Polytechnic Institution is highly satisfactory, and there would seem to be no reason to doubt the equal efficacy of the principle on the larger scale.-B.

HARPER AND JOYCE'S STOVES-MORE VICTIMS!

"For our parts, we would not sleep with one of these stoves in our bedchamber for one night, for ten times the sum we have heard mentioned as having been offered to the patentees for the invention. If the crevices of the windows and doors were suf

ficiently tight there need be no doubt as to the fate of the sleepers!"

Editorial remarks in Mech. Mag., vol. xxix.

Sir, The above prediction has just been most awfully realized, and two more human beings have been added to the list of victims.

The patentees of this precious discovery most positively asserted, that it gave out "neither smell nor noxious vapour;" the falsehood and fatal tendency of which assertion, I was among the first to point out to public attention. Notwithstanding the numerous cautions given in your pages, the patentees have continued to reiterate their assurances of the "safety and efficiency" of their stoves and fuel, although the dangerous character of these stoves and of the prepared charcoal has been demonstrated by yourself, as well as by M. Gay Lussac, Professor Everitt, and other first-rate chemists.

At an early period in the history of this invention, a gentleman who called at the establishment for the sale of these stoves was informed, "that a person had slept in a confined apartment, with one of these stoves burning all night, without experiencing the slightest inconvenience; he was likewise assured, that if the prepared fuel was used, not the slightest danger was to be apprehended!"

This is very wonderful—if true; and I can only say, that in my opinion the party had a very narrow escape. However, upon this fact (if fact it be), the patentees have continued to assert the perfect safety of these stoves and this

fuel, and one of the consequences of their heartless conduct is set forth in the following extract from the Weekly Dispatch of the 23rd ult. :—

"On Saturday morning last, much excitement prevailed in the neighbourhood of Church-street, Hackney, owing to the reported death, by suffocation from charcoal, of two youths in the employ of Mr. J. Long, the confectioner. From inquiries made, it appears that the unfortunate youths, whose names are Frederick Thomas Hersant, aged 19, and William Long, aged 17, were apprentices to Mr. Long. On Friday they complained of the coldness of their bedroom, which was situated over a bakehouse, and for the purpose of airing it, Mr. Long allowed them the use of a small self-smoke consuming stove, in which the PATENT CHARCOAL was burnt, with a strict injunction to remove it after the process of airing. This was done; but the poor fellows, anxious to impart warmth to their bedroom, and ignorant of the effect consequent on inhaling during sleep the noxious effluvia emitted from this charcoal, disregarded their employer's orders, and, in his absence, conveyed the stove into the room, and kindled a strong fire. They also, to make doubly sure their work of unpremeditated self-destruction, closed every aperture and crevice in the room, and, after making fast the door, retired to sleep-alas! to wake no more. Sur

prised at their non-appearance on Saturday morning, Mr. Long knocked at the bedroom door, and eventually, after many fruitless attempts to arouse them, forced his way into the room, and found them, to his surprise and grief, in an apparently lifeless state. Mr. Garrod, surgeon, was promptly in attendance, and pronounced Hersant to have been dead some hours. The other youth, Long, gave faint signs of animation, though little hope was entertained of his recovery. Mr. Garrod and the Messrs. Toulmin, surgeons, were unremitting in their attentions to him, but all that medical skill could devise proved unavailing. The unfortunate youth lingered until twelve o'clock at night (Saturday), when he expired. Monday an inquest was held at the Lion, Hackney, before Mr. Baker, on the bodies, and the above circumstances having been corroborated, a verdict of Accidental death' was returned."

The "infernal machine" which was moving to this catastrophe, was a Harper and Joyce's stove of the smallest size, which Mr. Long had purchased at a sale, where, with other rubbish, it had been brought "to the hammer."* The fuel

By placards posted about town, I perceive

employed, was the "prepared charcoal," purchased only about a fortnight before at Mr. Harper's shop in King Williamstreet, City, and therefore perfectly fresh and genuine. Fortunately for science, Mr. Long was not in the habit of using any charcoal in his business, nor was there any other than the "prepared" upon his premises.

You pertinently asked (at page 208 of your 29th vol.) "if the death of any party had taken place in consequence of full reliance on the assurances in the prospectus of the 'new stove' as to the innocuous nature of the 'prepared fuel,' would not the patentees have been indictable for manslaughter at the least ?"

How the jury could conscientiously reconcile their verdict of "accidental death," under the foregoing circumstances, with the evidence submitted to them, I know not-unless it was, that from the manner in which Mr. Long became possessed of the deadly instrument, he did not receive with it any "prospectus" or "directions for use,"

and could not therefore be said to have been misled by them.

Had there not been an implied reliance, however, upon the superior safety of the "prepared charcoal," Mr. Long would scarcely have sent from Hackney to the city for it, when plenty of common charcoal could be had at his own door.

Singularly enough, the very same paper from which the foregoing melancholy narrative is taken, contains in juxta-position to it, an advertisement of Joyce's stoves, in which they are described as such "excellent, useful, and convenient stoves, as no house should be without!" "Excellent"— for suicidal purposes; "useful"-for killing vermin; "convenient"-for disposing of burthensome relatives !

The most remarkable feature of the advertisement, however, is that no allusion whatever is made to the "prepared fuel;" which is fairly thrown overboard, by the following concluding notice :

Improvements have been made by the addition of pipes or chimneys suitable for offices, shops, warehouses, &c., for the purpose of burning coke!"

In this form it ceases to be Joyce's patent stove, and becomes an Arnott's stove of the very worst description; the

that "nearly three hundred" of these stoves are doomed to a similar fate at the Auction Mart on Thursday the 3rd of February, and following day!

MECHANICAL CHIMNEY SWEEPING.

Sir, It is with considerable reluctance that I venture to express an opinion upon the communication of Mr. J. A. Emslie in your last number, on the subject of mechanical chimney sweeping dictated, as that paper seems to be, solely by motives of humanity.

As the whole tenor of Mr. Emslie's remarks, however, are calculated to operate most prejudicially upon "the good cause" which he evidently has at heart, I must beg leave to place the subject in a more correct position before your readers.

Mr. Emslie sets out by supposing that at present we are wholly unprovided with any mechanical chimney, sweeping apparatus of a satisfactory character; he then goes on to enumerate defects (or supposed defects) of the apparatus heretofore employed for this purpose, and then suggests some machinery which he considers adapted to produce the object in view-a clean chimney.

But, that Mr. Emslie names Glass's machine, I should have supposed him as ignorant of its existence, as he evidently is of its superior capabilities. The fact is, that to this simple, but highly efficacious machine, we may with strict justice apply Mr. Emslie's own words, and say, that a more simple, safe, and efficacious plan for effecting the object in view, it will be difficult to find."

In the economy of its first cost,* facility in use, and universality of application, as well as in the cleanliness and efficiency of its operation, it leaves the suggested plans of Mr. Emslie immeasurably behind.

There is no chimney in existence capable of being swept by the weighted brush, that could not be swept far better, and with less injury, by one of Glass's

• The cost of one of Glass's machines complete, 30 feet in length, is only 21. 13s.; 40 feet 31. 28.; and 50 feet, 31. 11s.

101

machines; while there are innumerable chimneys to which the former is wholly inapplicable, that may, nevertheless, be very effectually cleansed by Glass's machine; among the other advantages of which must be enumerated, that of not requiring any previous provisions of pulleys or flue doors, except in the case of flues that are perfectly horizontal and quite beyond the powers of the weighted brush.

The pneumatic chimney-sweeping apparatus of Mr. Emslie is really beneath criticism; and his proposition to insert a damper in the upper part of the chimney, so as to close it in case of fire, is calculated to cause the very injury it is proposed to obviate. This highly mischievous plan is sometimes resorted to, by covering the chimney pot with wet sacks, blankets, &c., and when effectually done invariably produces disastrous results. I have seen elegant rooms with every article of furniture contained therein very seriously damaged in this manner. Stopping the draft of air at the lower part of the flue, and thereby checking combustion, is highly beneficial; but closing the upper orifice and driving all the heated air, smoke, and other products of combustion down into the apartment, is productive of serious mischief.

I am, Sir, yours respectfully,
WM. BADDELEY.

London, January 31, 1842.

IN

PILBROW'S CONDENSING CYLINDER ENGINE MR. PILBROW REPLY TO MR. CHEVERTON, MR. RADLEY, AND N. N. L.

Sir,-With your permission I will make a remark in answer to Mr. Cheverton's letter, (p. 439, in your vol. xxxv.,) which long since should have been done, had I been less engaged.

I think that Mr. Cheverton should not have made me "the occasion," if not "the subject," of that long communication, when he admits, in the first paragraph thereof, that "denies it not," speaking and quoting my remarks. We then both agree; and I must inform Mr. Cheverton, that I have ever given a maximum of my attention and dependance to practice rather than to theoretical deductions; and that when I made those remarks, I merely considered that the data for a calculation were the subject of

philosophy, and that if these were sound, the mathematics would not err in its conclusions of course, meaning, that if the whole of nature's laws, that were brought into action in any particular case, were not considered, or any made to act a part that did not do so in practice, that this was a philosopher's error, and one that could not be attached to the mathematician; therefore that the errors, multitudinous as they are that have almost choked our history of science and theory, all originated in the data or false philosophy, and not in the mathematical process. Mr. Cheverton "denies this not;' we both are, then, of the same sentiments, and as there has been enough said about this matter without my assistance, I shall only now thank Mr. Cheverton for his attention to me and mine.

But before closing I would observe, in reference to Mr. Radley's paper, that his opinions and his testimony are a proof of the correctness of my theory and calculations, rather than, as Mr. Radley supposes, a contradiction. I did not rest my argument upon the speed of the piston when actually descending, but I pointedly expressed the fact of the pause—a pause that the crank engine can never partake the advantages of a pause of one or two seconds after the eduction valve is opened to permit the steam to pass into the condenser, and be condensed before the steam valve is opened. This I know to be the fact, from accurate observation, and from the written communication of Mr. West, the engineer of Fowey Consols, which is printed in the pamphlet on my engine.

Yours respectfully,

The Green, Tottenham, January 24, 1842.

JAMES PILBROW.

P. S.-As I was going to post the above, I saw in your last, (No. 963,) a paper from Mr. Cheverton and N. N. L., which, with your permission, I will briefly notice.

In the passage directly referring to me, Mr. Cheverton uses these sentences: "Mr. Pilbrow's entire faith in it," &c.; "the sanguine, but deceptive expectations," &c.;

en

not being himself, perhaps, a mathematician ;" "blind indiscriminating admiration," &c. &c. &c. These various expressions are certainly not very complimentary to me or my abilities; and as Mr. C. knows, evidently, but little how far such are justly bestowed, he should not be so free in his allusions. Nowhere, I believe, in my papers or writings can be found any thing like " tire faith" in the hyperbolic curve, for I have merely considered that my engine offered the advantages of expanding the steam as low as should be found in practice economical-not further-though that was not said to be my object in the invention, but merely named as a minor advantage attending it. As to my "sanguine, but deceptive expectations," Mr. C. should first ascertain how sanguine I am, and next prove, or wait to see, how deceptive my expectations are, before he writes so positively, for in the whole of his voluminous observations, he has not in the slightest degree affected my engine. The next quotation, perhaps, is a matter of opinion or comparison, and therefore not likely to be decided to the satisfaction of all parties, nor usefully to any one, except to myself, who am satisfied upon the matter, for I find I am mathematician enough for all my purposes, which partake of as much practice as theory. As to "blind indiscriminating admiration," I can but feel obliged to Mr. Cheverton for such a compliment to my discretion and discernment, though I did not know that I had, in my late observations upon the subject which gave rise to such discussion, so shown my inability and ignorance.

In answer to N. N. L.'s 1st point, I beg to say that it is so, or we should alter the power of an engine by altering the stroke, though the consumption of the steam and all